docs(portal-behandel): ADR-0032 + demo note for the self-refreshing werkbak (refs #162)

Records why the werkbak polls rather than being pushed to (proposal #163):
nothing notifies the BFF either, so SSE/WebSockets would poll the domain
inside the BFF for the same freshness plus connection state, a dependency and
a stateful BFF. Names the ceiling (fixed 5s interval, per open page, keeps
polling in a hidden tab) and the upgrade path (publish task events, then swap
the interval for a stream).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/architecture/adr-0032-werkbak-live-refresh.md

@@ -0,0 +1,79 @@
+# ADR-0032: The werkbak refreshes itself by polling, not by a pushed stream
+
+- **Status:** Accepted
+- **Date:** 2026-09-04
+- **Deciders:** Respellion engineering
+- **Slice:** #162 (proposal #163). The issue titles it S-26; that id already belongs to
+  the self-service resume slice (#111), so #162 is the identifier that counts.
+
+## Context
+
+The werkbak (S-12) is a read of the open Flowable `Beoordelen` tasks: portal → BFF
+`GET /behandel/werkbak` → domain `Werkbak` query → workflow engine, each task enriched
+from its aggregate. A registration reaches `Beoordelen` **asynchronously**, only once the
+citizen supplies its documents and the DMN routes it (S-10a) — so it appears in a werkbak
+that is already open, and until now a behandelaar had to reload the page to see it.
+
+Three forces shape the mechanism:
+
+- **Nothing notifies anyone.** The trigger lives in Flowable. The domain does not publish
+  task events, and there is no bus between the domain and the BFF.
+- **The BFF is stateless** and sits behind each portal's nginx.
+- **This is the repo's first live-updating view**, so the choice sets a precedent.
+
+## Decision
+
+**The werkbak page re-reads the existing BFF endpoint on a fixed interval
+(`WERKBAK_REFRESH_MS`, 5 s) while it is open. No new endpoint, dependency or server-side
+state.**
+
+The refresh is a *background* read: it leaves the rows and the loading/failure states
+untouched until it has an answer, so a tick never flashes a spinner over rows a
+behandelaar is reading and a single failed poll never swaps the list for the error alert.
+A read that comes back also clears an earlier failure, so the view recovers on its own —
+the same reload this slice set out to remove would otherwise be needed to escape a
+transient error. Only a foreground read (on open, after a decision) speaks for whether the
+werkbak is readable at all.
+
+### Why not SSE or WebSockets
+
+Neither buys freshness here, because **nothing notifies the BFF either**:
+
+- **SSE** (`text/event-stream`) would mean a new streaming endpoint whose handler polls the
+  domain and forwards diffs — the same latency, plus connection lifecycle, nginx
+  buffering, and auth on a long-lived connection.
+- **WebSocket/SignalR** adds a dependency (CLAUDE.md §13) and makes the BFF stateful and
+  sticky-session-bound. A genuine push path would *also* need the domain to publish task
+  events. Warranted by high-frequency, bidirectional or fan-out-heavy traffic; the werkbak
+  is none of those.
+
+Polling meets the acceptance ("a registration can be seen in the werkbak once it is ready
+for review") in a handful of lines inside one component.
+
+- ponytail ceiling: a fixed 5 s interval, per open page, that keeps polling in a
+  background tab. Each tick costs one Flowable task query plus a store read per open task.
+- Upgrade path: publish task events from the domain, then swap the component's `interval`
+  for a stream. The endpoint contract and the component's rendering stay as they are;
+  gate on `document.visibilityState` first if request volume is the concern.
+
+## Consequences
+
+**Positive**
+
+- The outcome is delivered with no new endpoint, dependency, or server-side state, and no
+  service boundary moves.
+- Self-healing: a transient read failure no longer strands the view until a manual reload.
+- The e2e got *simpler* — the happy path waits for the werkbak row without reloading the
+  page, which is itself the live-refresh assertion.
+
+**Negative / costs**
+
+- Staleness is bounded by one interval (≤5 s) rather than instant.
+- One `GET /behandel/werkbak` per open werkbak per interval, including in hidden tabs.
+- The precedent is polling; a future view with genuinely high-frequency updates will have
+  to revisit this (see the upgrade path above).
+
+## Coupling rules touched (CLAUDE.md §8)
+
+None. The poll reuses the existing portal → BFF → domain read path: §8.3 (portals talk
+only to the BFF) and §8.2 (only the Workflow Client talks to Flowable) are unchanged.